[PATCH 03/14] iomap: Support THPs in BIO completion path

Matthew Wilcox (Oracle)
2020-10-14T09:22:28Z

bio_for_each_segment_all() iterates once per regular sized page.
Use bio_for_each_bvec_all() to iterate once per bvec and handle
merged THPs ourselves, instead of teaching the block layer about THPs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 62 ++++++++++++++++++++++++++++++------------
1 file changed, 44 insertions(+), 18 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 3e1eb40a73fd..935468d79d9d 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -167,32 +167,45 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
SetPageUptodate(page);
}

-static void
-iomap_read_page_end_io(struct bio_vec *bvec, int error)
+static void iomap_finish_page_read(struct page *page, size_t offset,
+ size_t length, int error)
{
- struct page *page = bvec->bv_page;
struct iomap_page *iop = to_iomap_page(page);

if (unlikely(error)) {
ClearPageUptodate(page);
SetPageError(page);
} else {
- iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len);
+ iomap_set_range_uptodate(page, offset, length);
}

- if (!iop || atomic_sub_and_test(bvec->bv_len, &iop->read_bytes_pending))
+ if (!iop || atomic_sub_and_test(length, &iop->read_bytes_pending))
unlock_page(page);
}

-static void
-iomap_read_end_io(struct bio *bio)
+static void iomap_finish_bvec_read(struct page *page, size_t offset,
+ size_t length, int error)
+{
+ while (length > 0) {
+ size_t count = min(thp_size(page) - offset, length);
+
+ iomap_finish_page_read(page, offset, count, error);
+
+ page += (offset + count) / PAGE_SIZE;
+ offset = 0;
+ length -= count;
+ }
+}
+
+static void iomap_read_end_io(struct bio *bio)
{
- int error = blk_status_to_errno(bio->bi_status);
+ int i, error = blk_status_to_errno(bio->bi_status);
struct bio_vec *bvec;
- struct bvec_iter_all iter_all;

- bio_for_each_segment_all(bvec, bio, iter_all)
- iomap_read_page_end_io(bvec, error);
+ bio_for_each_bvec_all(bvec, bio, i)
+ iomap_finish_bvec_read(bvec->bv_page, bvec->bv_offset,
+ bvec->bv_len, error);
+
bio_put(bio);
}

@@ -1035,9 +1048,8 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
}
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);

-static void
-iomap_finish_page_writeback(struct inode *inode, struct page *page,
- int error, unsigned int len)
+static void iomap_finish_page_write(struct inode *inode, struct page *page,
+ unsigned int len, int error)
{
struct iomap_page *iop = to_iomap_page(page);

@@ -1053,6 +1065,20 @@ iomap_finish_page_writeback(struct inode *inode, struct page *page,
end_page_writeback(page);
}

+static void iomap_finish_bvec_write(struct inode *inode, struct page *page,
+ size_t offset, size_t length, int error)
+{
+ while (length > 0) {
+ size_t count = min(thp_size(page) - offset, length);
+
+ iomap_finish_page_write(inode, page, count, error);
+
+ page += (offset + count) / PAGE_SIZE;
+ offset = 0;
+ length -= count;
+ }
+}
+
/*
* We're now finished for good with this ioend structure. Update the page
* state, release holds on bios, and finally free up memory. Do not use the
@@ -1070,7 +1096,7 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)

for (bio = &ioend->io_inline_bio; bio; bio = next) {
struct bio_vec *bv;
- struct bvec_iter_all iter_all;
+ int i;

/*
* For the last bio, bi_private points to the ioend, so we
@@ -1082,9 +1108,9 @@ iomap_finish_ioend(struct iomap_ioend *ioend, int error)
next = bio->bi_private;

/* walk each page on bio, ending page IO on them */
- bio_for_each_segment_all(bv, bio, iter_all)
- iomap_finish_page_writeback(inode, bv->bv_page, error,
- bv->bv_len);
+ bio_for_each_bvec_all(bv, bio, i)
+ iomap_finish_bvec_write(inode, bv->bv_page,
+ bv->bv_offset, bv->bv_len, error);
bio_put(bio);
}
/* The ioend has been freed by bio_put() */
--
2.28.0